Reply To: Executing the mc simulation of polyalanine fragment

python syntax for a method is:

def function_name( function_input_variables):

the “def perturb_bb = function(pose):” will cause a syntax error (as noted above), use the “return” keyword if you want to return the value of a variable “perturb_bb”
the syntax you entered is similar to a lambda function but both methods you used to execute the script are correct